Structure-dependent lipolysis kinetics in advanced food emulsions

In emulsion design, it is of paramount importance to study digestive fate to evaluate the evolution of lipid hydrolysis and the bioavailability of possible bioactive compounds. To study how the emulsion structure and polyphenol incorporation affect lipid digestion rate, three advanced oil-in-water food emulsions (i.e., Pickering, cold-filled and hot-filled gel emulsions) were digested according to the static in vitro INFOGEST 2.0 protocol and compared with a simple emulsion. The emulsions were tested both with and without the addition of a commercial polyphenol extract produced from olive oil industry by-products. No interaction between polyphenols and triacylglycerol hydrolysis was found at the concentration used, while the different emulsion structures affected the lipolysis rate, especially at the end of the gastric phase, where the cold-filled gel emulsion produced with citrus fiber showed the highest amount of free fatty acid (FFA) released (18.5 ± 0.9%). No differences were found in terms of FFA release at the end of the intestinal phase, but significantly lower amounts of mono- and diacylglycerol compounds were found in the cold-filled gel emulsion with citrus fiber (18.7 ± 4.1%). These results are important in view of possible targeted emulsion applications that can require different lipid digestion rates.